1. Field of the Invention
This invention relates, generally, to fabric seams and more particularly, to a liquid proof (e.g. waterproof) seam and method of manufacture.
1. Prior Art
Many attempts have been made to make liquid proof, particularly waterproof, articles such as raincoats, jackets, and similar outerwear as well as tents, outdoor equipment, tarpaulins and the like. Accordingly, the technology has developed to the point where reusable woven or knit fabric materials offer varying degrees of liquid proofing depending upon the characteristics of the material utilized and the use to which the material will be put.
Of recent date, a new class of garments have become important. This class relates to surgical, medical, laboratory and other types of garments, worn by personnel that have interaction with patients; as well as laundry bags, containers and the like for such medical uses. More particularly, with the attention of the clinical community focusing on the transmission of infectious diseases by blood and body fluids, the use of personal protective clothing has increased significantly. Comfort of such clothing has also become an important consideration.
While some materials are totally impervious to fluids and the like, they are generally unsuitable in that they do not breathe and/or are difficult or generally uncomfortable to wear. Furthermore, since materials of this nature cannot be sterilized by traditional methods, their use is prohibited. As a result, a number of materials have been developed which offer excellent comfort and performance characteristics. Examples of these fabrics are FASHION-BLOC and FASHION-SHIELD manufactured and produced by Superior Surgical Mfg. Co., Inc. of Seminole, Fla. These materials are very effective when worn as protective apparel by a health care worker during a procedure.
Protective apparel is also used to reduce the risk or exposure of a worker's skin or mucous membranes to blood and body fluids containing visible blood and other fluids to which universal precautions for the transmission of HIV ("Universal Precautions") apply. Such precautions are relatively standard in the health care industry for a variety of reasons, the most recent and perhaps most important being the potential contraction of Acquired Immunity Deficiency Syndrome. i.e., AIDS.
However, while fabric construction has advanced greatly, the liquid proofing, e.g., waterproofing, of seams in these items has continued to present problems. Moreover, these types of items are generally only cost effective when repeated usage is possible. Therefore, they must be able to withstand the rigors of numerous institutional type processing cycles (laundering, drying and ironing), sterilizations and the like. Therefore, seam makeup including thread, overall construction and other fluid-resisting materials must similarly be able to withstand such abuse.
Many attempts have been made to produce waterproof, water resistant or liquid proof seams. For example, U.S. Pat. No. 4,604,152, "Method of Making a Stitched and Bonded Seam" to Liukko describes a liquid proof seam formed by interposing a thermal adhesive between overlapping edges of material. However, this has a significant drawback in that the joint is formed solely by the thermal adhesive. Once a portion of this type seam separates, for any one of a variety of reasons, a zippering effect will result, i.e. the entire seam will fail as stress is placed on it.
U.S. Pat. No. 4,593,418, "Method and Seam Construction to Significantly Reduce Seam Leakage" to Simon describes an elastomeric strip interposed between sheets of material. The elastomeric material is sewn to the seam, and surrounds and seals the thread as it passes through the seam. However, this is also somewhat unsatisfactory in that, since no bonding occurs between the elastomer and fabric, the integrity of the liquid proof seam is entirely dependent upon the structural integrity of the sewing. Therefore, should the thread become loosened or broken, fluids may wick or pass by or through the seam itself.
U.S. Pat. No. 4,561,128 "Fusing Apparel Seams" to Zimmerman is directed to a method for fusing seams for the purpose of providing aesthetically pleasing, i.e. straight and flat, seams. This patent does not teach or suggest waterproofing or the problems associated therewith.
U.S. Pat. No. 2,115,368 "Seam" to Lustberg describes a waterproof seam by interposing a water repellant material between two layers of waterproof material. A water repellant thread is utilized to sew the seam. The integrity of this seam is dependent upon the mechanical integrity produced by thread. Therefore, should the thread become loose or ripped, passage for fluids is made possible.
While all of the above offer solutions to the problem of enhancing the integrity of seams, they are all lacking in one respect or another.